Field of the Invention
The present invention relates to a front wheel steering apparatus operable in response to the driver's steering effort applied thereto to steer a set of steerable front road wheels in a wheeled vehicle.
Description of the Prior Art
In general, a conventional front wheel steering apparatus of this kind includes an input shaft arranged to be rotated by the driver's steering effort applied thereto, an output member operatively connected to a set of steerable front road wheels by means of a steering linkage, and an interconnecting mechanism in the form of a rack and pinion mechanism, a ball screw mechanism or the like for operatively interconnecting the input shaft to the output member. In the interconnecting mechanism, however, a displacement stroke ratio of the output member relative to a rotation angle of the steering wheel is constant as shown by a broken line in FIG. 3. For this reason, the driver's feel in steering operation becomes insufficient when the steering wheel is steered at a large angle from a neutral position, and a maximum rotation angle of the steering wheel necessary for steering the front road wheels at a desired maximum angle becomes larger (for example, 540 degrees). In the case that the displacement stroke ratio of the output member is increased to overcome the above problem, the driver's feel in steering operation becomes excessive at an initial stage adjacent the neutral position of the steering wheel.